JP2011155022A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating cooker such that interference sounds (beat sounds) will not bother a user, when all three stoves of the induction heating cooker are set as induction heating types. <P>SOLUTION: In the induction heating cooker, including a first induction heating coil 13a, a second induction heating coil 13c, a plate 3 covering top of the coils for placing a cooking pan thereon, and an inverter 72 supplying electric power to the induction heating coils, in which an output control is performed by varying electric frequencies in the induction heating coils, the lowest frequency in the frequency band used for the second induction heating coil 13c is set higher than the highest frequency in a frequency band used for the first induction heating coil 13a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an induction heating cooker.

  Conventionally, the majority of heating cookers that heat cooking pots use a gas cooker or other flame as a heat source.

  In recent years, the trend of so-called all-electric homes, in which all home appliances are electrified, is becoming prominent. As part of this, an electromagnetic induction heating cooker that uses the eddy current of the pot to heat the pot itself has been reviewed. As an induction heating cooker, the two-sided stove arranged at the left and right in front of this is an induction heating type, and the stove arranged behind these stoves is a heater type using a radiant heater or the like. A heating cooker is common.

  By the way, since the heater type stove provided near the center of the rear part of the main body is a heater type, the pot is heated by heat conduction. This is a structure in which a plate on which a pan is placed is heated by a heater and the heat is transmitted to the pan. This has the disadvantage that the plate becomes hot. This is contrary to the advantage of the induction heating method in which the stove and its surroundings do not get hot.

  Thus, a cooker that uses all three stoves with induction heating is desired. Patent Document 1 describes a heating cooker in which a stove provided in the center of the main body is also of an induction heating type, and all of the stoves are of an induction heating type.

  By the way, as described in the prior art of Patent Document 2, such an induction heating type thermal power (output) is controlled by controlling the switching elements that constitute the inverter, whereby the current flowing through the induction heating coil and the resonance capacitor is controlled. The frequency is adjusted by changing the frequency (frequency control method). However, as described in Patent Document 2, when the cooker has a plurality of induction heating coils, there is a problem that interference sound (beat sound, beat) is generated. When a pan is heated and cooked by operating a plurality of induction heating coils, when the pan is heated with different heating power, each pan is vibrated by receiving an alternating magnetic field having a different frequency from each induction heating coil. Since the frequency of this vibration is higher than the audible frequency, there is no problem.

  In order to solve this problem, in Patent Document 2, the thermal power control is performed by changing the duty to be energized without changing the frequency (duty control method), thereby eliminating the interference sound so as to eliminate the difference in oscillation frequency. I am doing so.

  Further, in Patent Document 3, in order to solve the above-described problem of interference sound, a fan motor in which the frequency of interference sound (difference in frequency of electric power applied to two induction heating coils) cools the induction heating cooker. It is described that selection is made so that the frequency band of sound is the same (Patent Document 4 also describes a similar technique), or that the frequency is selected so that the frequency of the interference sound is larger than the audible frequency band. ing. Furthermore, Patent Document 4 describes that the interference sound is reduced by taking a distance of a predetermined distance or more with respect to the relationship between the distance between the two induction heating coils and the interference sound.

JP 2004-319350 A Japanese Patent No. 2532565 JP 58-142783 A JP-A-2-288184

  The interference noise reduction techniques described in Patent Documents 2 to 4 are realized by fixing the frequency of the current flowing through the induction heating coil. That is, the thermal power is adjusted by duty control performed by controlling the duty while fixing the current frequency. However, this duty control method has a problem that the circuit configuration is larger than that of the frequency control method, and it is desirable to employ the frequency control method.

  However, there is a problem that interference sound is generated when all the three-hole stoves described in Patent Document 1 are induction heating type. As described above, in the frequency control method, since the heating power generated by the induction heating coil is variable by changing the frequency, the interference frequency cannot be set to a fixed value as described in Patent Documents 2 to 4. . For this reason, when all the three stoves of the induction heating cooker incorporated in the system kitchen are set to the induction heating method, and the thermal power control is set to the frequency control method, an interference sound is inevitably generated.

  An object of the present invention is to provide an induction heating cooker in which an interference sound (beat sound) is not noticed by the user when all of the three stoves of the induction heating cooker are induction heating type. .

  The above object includes a first induction heating coil, a second induction heating coil, a plate that covers the top surface of these induction heating coils and places a cooking pan, and an inverter that supplies power to these induction heating coils. In the induction heating cooker that performs the output control of the induction heating coil by making the frequency of the current energized variable, the second induction heating coil has a higher frequency than the maximum frequency of the frequency band used for the first induction heating coil. When the minimum frequency of the frequency band to be used is set higher by 15 kHz or more, and when a power lower than the minimum power of the first induction heating coil is continuously applied with the drive frequency of the inverter means being the maximum frequency, This is achieved by using an induction heating cooker that also uses on / off control of energization of the inverter means.

  The above object includes a first induction heating coil, a second induction heating coil, a plate that covers the top surface of these induction heating coils and places a cooking pan, and an inverter that supplies power to these induction heating coils. In the induction heating cooker that is performed by making the frequency of the current that is energized to control the output of the induction heating coil, each induction heating coil is formed by winding a coil wire in which strands are twisted, The minimum frequency of the frequency band used for the second induction heating coil is set higher by 15 kHz or more than the maximum frequency of the frequency band used for the first induction heating coil, and the wire diameter of the second induction heating coil is set to Induction in which the wire diameter of the first induction heating coil is smaller than that of the first induction heating coil, and the number of strands of the second induction heating coil is larger than the number of strands of the first induction heating coil. It is accomplished by a heat cooker.

  As described above, according to the present invention, it is possible to provide an induction heating cooker in which the interference sound (beat sound) is not noticed by the user when all the three stoves of the induction heating cooker are induction heating type. it can.

It is a perspective view of the state which stored the built-in type induction heating cooking appliance in the system kitchen. It is explanatory drawing which shows the upper surface of a heating cooker. It is explanatory drawing which shows an example different from FIG. It is explanatory drawing which shows the front surface of a heating cooker. It is explanatory drawing which shows the state which removes the plate of the upper surface of a heating cooker, and can see a heating coil. It is sectional drawing which shows the internal structure seen from the side surface of the heating cooker. It is explanatory drawing which shows the structure of a roaster. It is explanatory drawing which shows the roaster operation part in the kangaroo pocket part of a heating cooker. It is explanatory drawing which shows the upper surface operation part of a heating cooker. It is a block diagram explaining the heating part of a heating cooker, and its control. It is explanatory drawing for the sum total of the power consumption at the time of cooking of a heating cooker to keep below maximum power consumption. It is explanatory drawing which shows the specific circuit of an inverter. It is a figure which shows the dimension of a top plate. It is a figure explaining the relationship between the distance between coils, and a beat sound. It is a figure explaining the relationship between a drive frequency and a thermal power (output).

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 10 show an embodiment of the induction heating cooker of the present invention. The cooker shown in FIG. 1 is a built-in induction heating cooker in which three pan mounting portions 6 a, 6 b, 6 c are provided on a plate 3.

  In addition, the present Example is not limited to the built-in type that fits in the kitchen, but may be a stationary heating cooker that is placed in the kitchen.

  The main body 2 of the heating cooker is incorporated by being dropped from the upper surface of the system kitchen 1 and installed. After installation, a roaster (grill) 4 and an operation panel 5 described later of the heating cooker 2 can be operated from the front surface of the system kitchen 1.

  A cooking pan (not shown) for cooking is placed on a plate 3 made of heat-resistant glass or the like disposed on the upper surface of the main body 2.

  A cooking pan (not shown) can be cooked by being placed on the placement portion 6 drawn on the plate 3. The placement unit 6 has a placement unit right 6a and a placement unit left 6b arranged in front of the upper surface of the plate 3 on the upper surface of the main body 2, and is placed in the back (center rear) between the placement units 6a and 6b. The center 6c is arranged. And the heating coil unit 25 mentioned later for heating a cooking pot below each mounting part 6 on both sides of the plate 3 is each installed.

  The placement center 6c is a place where it is difficult to reach the position of the cook. For this reason, when the cooking pan is placed on the placement unit right 6a and the placement unit left 6b in the foreground, if the hand is extended to the placement unit center 6c, the placement unit right 6a and the placement unit left 6b It is difficult to perform cooking by moving the hand at the placing portion center 6c due to steam generated during cooking from the cooking pan placed. Accordingly, the type of cooking performed at the placement portion center 6c is suitable for cooking that does not require the chef to move much, mainly cooking such as stew or heat retention. Moreover, since the heating power is low and the maximum power consumption is limited, the heating power of the heating coil 13c installed in the mounting portion center 6c corresponds to the mounting portion right 6a and the mounting portion left 6b. The heating coil right 13a and the heating coil left 13b are set so that the power consumption is reduced.

  In FIG. 2, it is the display 97 which shows that all the three heating parts (stove) are an induction heating coil. Suppose that the display was provided at the center of the plate 3 or on a straight line connecting the center of the heating coil right 13a and the heating coil left 13b, and the cooking pot was put on the mounting part and exhibited at the store. In addition, the display is not hidden, and it is possible to easily recognize that the three heating methods are the induction type by looking at the display arranged at the substantially central portion of the plate 3.

  A line 98 is a line connecting from the display 97 to the three placement parts. By drawing the three meanings included in the character “3IH” of the display 97 and three lines connected to the three placement parts, It can be seen at a glance that anyone can see that the heating method of the mounting portion is the induction method indicated by the display 97.

  1 and 2, a frame 14 is provided to protect the peripheral end surface of the plate 3. It consists of a frame front 14a attached to the upper upper edge of the front side of the plate 3, a frame rear 14b attached to the rear upper edge of the plate 3, a 14c attached to the right upper edge, and a frame left 14d attached to the left upper edge. ing. In this example, the frame is divided into 4 pieces, but it can be integrated, 2 pieces or any number of pieces, and it is not necessary to attach it to the 4 sides of the plate 3. Only two sides or only two sides on the left and right sides may be used.

  Inside the main body 2, a heating coil unit 25, which will be described later, which is a heat generating member, and electronic components are provided, and an air inlet 7 for sucking air from the outside of the main body 2 is provided to cool them. The intake port 7 is located on the right side of an exhaust port 8 (described later) on the rear frame 14 b on the upper surface of the main body 2.

  The air sucked through the air inlet 7 is discharged to the outside from the air outlet 8 after cooling a heating coil unit 25 and an electronic component (described later) that generate heat inside the main body 2. Further, waste heat of the roaster 4 described later is also discharged from the exhaust port 8 at the same time, and the exhaust port 8 is provided on the side of the roaster 4 on the rear frame 14b on the upper surface of the main body 2.

  Since the roaster 4 is used to bake fish, pizza, etc., it is arranged on the left or right side of the front surface of the main body 2. In the present embodiment, it is arranged on the left side toward the front surface of the main body 2. Further, since it is not dedicated to grilled fish, the roaster 4 may be called a grill or an oven.

  The roaster 4 will be described in detail with reference to FIG. The cooking chamber 26 has a box shape with an open front, and an upper heating element 27 and a lower heating element 28 made of a heating element such as a sheathed heater are installed therein. An exhaust outlet 29 is provided at the upper rear of the cooking chamber 26. Although the upper heating element 27 and the lower heating element 28 are provided as the heating elements, only the upper heating element 27 may be provided. However, in this case, it is necessary to turn it over while the food 30 is being baked.

  The roaster door 32 that closes the front opening of the cooking chamber 26 has a handle 11 attached to the front side and a tray 31 attached to the back side. The saucer 31 is accommodated in the cooking chamber 26 so as to be freely inserted and removed from the front opening. On the other hand, a grill 33 is placed in the tray 31, and a food item 30 such as fish is placed thereon.

  The cooking chamber 26 is provided with an air purification catalyst 34 for purifying smoke and odor generated when the food 30 is baked. The air purifying catalyst 34 is attached so that smoke and odor entering from the exhaust outlet 29 always pass through the air purifying catalyst 34.

  When the exhaust fan 36 is operated, air flows into the cooking chamber 26 through the air intake 42 provided between the tray 31 and the roaster door 32. The inflowing air is discharged to the outside from the exhaust port 8 through the air purification catalyst 34 and the exhaust passage 35 together with smoke and smell generated in the cooking chamber 26. Due to the catalytic action of the air purification catalyst 34, the odor and smoke generated in the cooking chamber 26 are forcibly exhausted from the exhaust port 8 while being reduced according to the ability of the catalyst.

  A catalyst heater 37 for heating the air purification catalyst 34 is installed in the vicinity of the air purification catalyst 34 in the cooking chamber 26. As a result, the air purification catalyst 34 is heated and a catalytic action is exhibited.

  The temperature in the cooking chamber 26 is detected by temperature detection means 38 such as a thermistor provided at the upper portion of the cooking chamber 26 on the front opening side and the lower portion of the side surface of the tray 31.

  In the case of a single-sided grill provided with a heater only at the top, water must be put into the saucer 31 and baked in order to prevent the temperature of the saucer 31 from rising. In this embodiment, since double-sided baking is used, water cannot be added. Therefore, in order to cool the tray 31, a cooling passage 39 is provided below the tray 31. When the suction fan 40 rotates, the air flowing in from the air intake 42 flows through the lower part of the receiving tray 31, cools the receiving tray 31, and then exhausts from the exhaust port 8 through the back side of the cooking chamber 26.

  The exhaust fan 36 and the suction fan 40 are driven by a motor 41 provided at the lower part of the rear frame 14b. The exhaust fan 36 and the suction fan 40 are directly attached to the shaft of the motor 41. The motor 41 is cooled by a self-cooling fan 43 provided on the shaft on the other end side of the motor 41.

  The motor 41 and the self-cooling fan 43 are disposed in a heat shield chamber 44 provided at the rear of the main body 2 at the lower part of the rear frame 14b. The heat shield chamber 44 is provided with an air inlet 45 on the bottom and side surfaces of the main body 2, air is taken in from the air inlet 45, and the cooled air flows out from a discharge hole 46 provided on the upper surface. .

  Next, the heating coil will be described with reference to FIG. A heating coil unit 25 for heating a cooking pan (not shown) is composed of a heating coil 13, a coil base 24, and ferrite (not shown). The heating coil unit 25 is disposed below the plate 3 of each placement unit 6 so that a certain gap is opened between the plate 3 and the heating coil 13. This gap is for allowing cooling air to be described later to flow. A heating coil unit right 25a is provided below the placement portion right 6a, a heating coil unit left 25b is provided below the placement portion left 6b, and a heating coil unit center 25c is provided below the placement portion center 6c. Yes.

  The winding of the heating coil 13 employs litz wire to suppress the skin effect. A voltage of several tens of kHz and several hundreds of volts is applied to the heating coil 13 from an inverter 72 described later in order to heat a cooking pan (not shown).

  The coil base 24 fixes the heating coil 13 from below, and ferrite (not shown) is embedded in the coil base 24.

  Temperature detection of the pan such as during automatic cooking is performed by a temperature detection element 21 embedded in the heating coil 13. The temperature at the bottom of the pot is indirectly detected via the plate 3. In addition, although the temperature detection element 21 is installed in the heating coil unit right 25a and the heating coil unit 25b in the figure, the temperature can be managed by keeping the heating coil in the heating coil unit center 25c. It becomes like this.

  Next, the inverter for exciting the heating coil and its cooling will be described with reference to FIG. FIG. 6 is a vertical cross-sectional view of the heating cooker main body 2, and a substrate on which an inverter is mounted and a heat radiation fin that is a cooling mass for cooling the heating element are described in the lower center portion. The left and right inverter boards 18 on which the inverters for driving the left and right heating coils 13a and 13b are mounted are arranged at the bottom, and the central inverter board 17 for driving the heating coil center 13c is arranged at the upper stage. In general, the upper stage is likely to receive the heat of the lower stage, but the heating coil center 13c has a lower maximum heat input than other coils, so the amount of heat generation is small. For this reason, the inverter board | substrate 17 which drives the heating coil center 13c was distribute | arranged to the upper stage. As shown in FIG. 10, electronic components for driving the heating coil right 13a and the heating coil left 13b are mounted on the inverter board 18, and an inverter right 72a, an inverter left 72b, and an inverter control means right 73a, which will be described later, are mounted. And inverter control means left 73b are mounted.

  Returning to FIG. 6, each board is provided with heat radiation fins 22 and 23 for efficiently exchanging heat generated by the electronic components with cooling air to lower the temperature of the electronic components. Is smaller than the radiation fin 22.

  As described above, the maximum heating power of each heating coil is set to be smaller in the heating coil center 13c than the heating coil right 13a and the heating coil left 13b. Therefore, the power consumption in the central inverter board 17 is larger than that in the left and right inverter boards 18. small. For this reason, the amount of heat generated by the electronic components is also smaller than that of the left and right inverter boards, and the radiating fins used for cooling can be reduced. For this reason, the small radiating fins 23 are used for the central inverter board 17 and the large radiating fins 22 are used for the left and right inverter boards 18.

  Each component that generates heat is cooled by the air sent by the blower fan 20. The outside air for cooling sucked from the air inlet 7 flows through the board case 15 for housing the left and right inverter boards 18, the central inverter board 17 and the control board 19, and takes heat from the heat radiation fins 22 and 23. Each heating coil is cooled and discharged from the exhaust port 8 to the outside.

  The substrate case 15 shown in FIG. 5 is installed below the heating coil unit 25 opposite to the heating coil unit on which the roaster 4 is installed. In this embodiment, the heating coil unit is placed below the right 25a, and the substrate is stored in the substrate case to protect the substrate from the radiant heat from the heating coil 13 and the roaster 4 during cooking. In addition, an air passage through which the cooling air passes is formed so that the cooling air is efficiently distributed to the heating coil unit and the upper surface display unit.

  Since all the circuits cannot be accommodated in the substrate case 15 described above, one part of the circuit that does not generate heat extremely, one part that does not pass a large current, a control circuit that organizes the entire system of the heating cooker, and a control unit for the inverter circuit Is mounted above the substrate case 15.

  Next, the operation of the heating coil 13 will be described with reference to FIG. The operation of the heating coil 13 is performed by the upper surface operation unit 9 provided on the front frame 14 a before the plate 3. Corresponding to the placement part right 6a, the placement part center 6c, and the placement part left 6b on which the pan is placed, the upper surface operation part right 9a, the upper surface operation part center 9c, and the upper surface operation part left 9b are arranged from the right. This arrangement is such that the operator can intuitively understand the relationship between the pan and the operation unit.

  As is apparent from the figure, the upper surface operation unit right 9a and the upper surface operation unit left 9b have the same key arrangement. This is a result of reducing the function of the heating coil center 13c as compared with other heating coils.

  Hereinafter, the operation of the heating coil right 13a will be described as a representative. Reference numeral 48 denotes a cut / start key for starting and stopping cooking, and the LED lamp 53 is lit during cooking.

  The heating power for cooking is selected by the heating power key 49. The keys are divided into four steps: hot, low, medium, and high, and each key is provided so that the necessary firepower can be set with a single operation. As for the standard of each thermal power, for example, when the thermal power can be adjusted in 12 steps at the maximum, the relationship between each thermal power and power consumption is equivalent to 100 W in the “1” stage, equivalent to 200 W in the “2” stage, and 300 W in the “3” stage. “4” stage is 400 W, “5” stage is 500 W, “6” stage is 800 W, “7” stage is 1.1 kW, “8” stage is 1.4 kW, “9” stage is 1.6 kW, “ The “10” stage is 2 kW, the “11” stage is 2.5 kW, and the “12” stage is 3 kW. The numbers at each stage are numbers that are displayed on the upper surface display unit 10 to be described later as an indication of the thermal power. In addition, the relationship between the thermal power notation and the actual stage display is “1” for hot fire, “2”, “3”, “4”, “5” for low heat, “6”, “7”, “8” for medium fire. “9” and “10” are assigned to the high fire, and “11” and “12” are assigned to the high power. The fire key 49 can be directly set to a representative fire power of four stages of fire power, the hot key 49a is "1", the low fire key 49b is "4", the medium fire key 49c is "7", and the high fire key 49d is "10". The LED lamp 54 in the set key portion lights up.

  Reference numeral 51 denotes a timer key that is selected mainly when performing timer cooking such as boiling or heat retention. Reference numeral 52 denotes a menu key for selecting cooked rice, fried food, kettle, etc. for automatic cooking. When the menu key 52 is pressed, a menu is displayed on the upper surface display unit 10 to be described later, and is displayed each time the menu key 52 is pressed. The selected menu is switched, and the menu to be used is selected.

  Moreover, the setting key 50 can be used to adjust the heating power, set the time during timer cooking, set the amount of rice during cooking, set the automatic cooking finish, and set the oil temperature when frying. . This setting key 50 is composed of an UP key 50a for increasing the quantity at the time of setting and a DOWN key 50b for decreasing, and indicates that the setting key 50 is valid when the LED lamp 55 in the setting key 50 section is lit. When turned off, it is invalid.

  For example, a case where the heating power is adjusted with the setting key 50 will be described. First, the medium fire key 49c is pressed to set the heating power to “7”. Thereafter, when the UP key 50a of the setting key 50 is pressed twice, the number indicating the thermal power displayed on the upper surface display unit 10 to be described later is changed from “7” to “8”, and from “8” to “9”. High fire “9” is set. Along with this, the LED lamp 54 of the fire power key 49 also turns off the LED lamp of the medium fire key 49c and the LED lamp of the high fire key 49d. The same applies to other settings. For example, the operation of the setting key 50 after the timer key 51 is pressed is for time setting. Since the upper surface operation unit left 9b has the same operation and arrangement as the upper surface operation unit right 9a, description thereof will be omitted.

  Next, the upper surface operation unit center 9c will be described. The main cooking of the mounting portion center 6c is heat insulation and stew. The reason for this is as described above. Therefore, the heating power of the heating coil center 13c is designed to be smaller than the heating power of other heating coils. For this reason, it is sufficient for the heat power notation to be low heat, low heat, medium heat, and even if the setting key 62 is cyclic type, it will return to its original state when it is pressed three times at maximum, so that each heat power like the two heating coils 25a, 25b on the front side There is no thermal power setting key corresponding to. Thereby, the installation space for the key can be secured. In addition, the content of the automatic cooking menu is limited to stew and heat insulation, etc., because the design is limited to the thermal power.

  2 and 9, the plurality of keys arranged on the upper surface operation unit 9 are arranged in a line in the width direction of the main body 2 on the front frame 14a. From the right toward the main body 2, the upper surface operation unit right 9a, the upper surface operation unit center 9c, and the upper surface operation unit left 9b are arranged in this order. However, if the keys are simply arranged in a horizontal row, the boundary becomes difficult for the user to understand. For this reason, it is necessary to devise such that each upper surface operation unit is surrounded by a frame, divided into different colors, and divided into key colors. In this embodiment, each upper surface operation unit is surrounded by a frame line, and the lowest key is provided between the upper surface operation unit right 9a and the upper surface operation unit center 9c, and between the upper surface operation unit center 9c and the upper surface operation unit left 9b. The space | interval more than 1.5 width | variety was opened. As a result, the operator has a visual and tactile effect that the operation key classification is easy to understand.

  Next, a display that reflects the result of the above-described operation will be described. The contents corresponding to the key operation of the upper surface operation unit 9 are displayed on the upper surface display unit 10. The contents to be displayed are the display of the thermal power set by the upper surface operation unit 9, the time display for timer cooking, the display of the set oil temperature for fried food, and the like. The upper surface display unit 10 is disposed on the near side of the plate 3 placed on the upper surface of the main body 2 and on the back side of the plate 3. Accordingly, when viewing the display, the display portion is provided through the plate 3, so that the display portion of the upper surface display portion 10 is processed so that the display content can be seen through the plate 3. In addition, the backlight color of the display unit is set so that the set thermal power can be easily understood from the image. In the present embodiment, the flash fire and the low fire are displayed in green, the medium fire is displayed in orange, and the high fire and high power are displayed in red.

  In the above embodiment, the upper surface display unit right 10a, the upper surface display unit center 10c, and the upper surface display unit left 10b are divided corresponding to each upper surface operation unit 9, and the arrangement of each upper surface display unit is a straight line along the frame front 14a. However, in order to improve the visibility, the upper surface display center 10c may be disposed closer to the mounting portion center 6c than the upper surface display portion right 10a and the upper surface display portion left 10b.

  The upper surface operation unit 9 and the upper surface display unit 10 are provided for each mounting unit 6 on the plate 3. When the line of sight is linearly moved from the mounting unit 6 toward the front side, It arrange | positions so that the upper surface operation part 9 and the upper surface display part 10 corresponding to the mounting part 6 may exist, and is arrange | positioned so that the upper surface operation part 9 may be located in the cooker side rather than the upper surface display part 10. FIG. .

  Next, the operation unit related to the roaster 4 will be described. As shown in FIG. 1, an operation panel 5 on which a roaster operation unit 12 (described later) and a roaster display unit 65 for operating the heating condition of the roaster 4 are arranged is arranged on the right side of the roaster 4. The operation panel 5 is located in front of the main body 2 and is a kangaroo type opening / closing mechanism. FIG. 1 shows a state where the operation panel 5 is closed, and FIG. 2 shows a state where the operation panel 5 is opened. The operation of the roaster operation unit 12 and the confirmation of the roaster display unit 65 can be performed with the operator standing while cooking.

  Various keys will be described with reference to FIG. Fish grill and gourmet (various automatic cooking) are selected by the grill selection menu key 66. Each time the fish roast key 66a is pressed, the round, fillet, string, tsukeyaki, and manual LED lamps displayed on the roaster display unit 65 are cyclically switched to select a menu that is lit. Similarly, when the gourmet key 66b is cyclically pressed, the lighting state of the pizza, foil baking, and gratin LEDs is switched, and the menu that is lit is selected.

  After selecting the menu, the cooking finish (baking) can be set with the setting key 68. Each time the up key 68a or the down key 68b is pressed, the weak / medium / strong LED lamps of the roaster display section 65 are turned on to enable selection. Then, the cooking time can be selected by pressing the timer key 69. Also at this time, the timer time (heating end time) can be selected by the setting key 68. When various settings are completed, the cooking is started by pressing the OFF / START key 67 for starting, stopping, and canceling the cooking of the selected menu. Even when the timer is set, cooking can be stopped by pressing this OFF / START key.

  Moreover, in the cooking-by-heating machine which concerns on a present Example, the function which prevents mischief by a child is provided. It can be unlocked by holding the child lock 71 for 3 seconds and then pressing again for 3 seconds.

  Next, the control will be briefly described with reference to FIG. The operation / display unit 75 includes the upper surface operation unit 9, the roaster operation unit 12, the upper surface display unit 10, and the roaster display unit 65 described so far. Menus, heating power information, cooking start / off information, etc., input by the operation unit of the operation / display unit 75 are sent as an input signal 80 to the control unit 74 described later, information recognized by the control unit 74, cooking progress, etc. Is sent to the operation / display unit 75 as a display signal 79 and displayed on the upper surface display unit 10 and the roaster display unit 65.

  The control unit 74 controls the heating unit based on the contents set by the operation / display unit 75 and a program such as automatic cooking incorporated in advance. Based on the set contents, setting information on the start, stop, and heating power of cooking is sent to an inverter control means 73 or a heater control means 82 to be described later via a control signal 78 (control signal 85). And temperature information is received by receiving the control signal 78 (control signal 85) which carried temperature information from the temperature detection element 21 (temperature detection means 38) which detects the temperature provided in the heating part. Although not shown in the block diagram, the blower fan 20 is also controlled, and the blower fan is operated during cooking.

  The inverter control means 73 monitors and corrects the setting of power to the heating coil 13, the start and stop of energization, and the power consumption of the heating coil 13 based on instructions from the control means 74. The inverter 72 is controlled (described later) by sending an inverter control signal 76 to the inverter 72. For monitoring and correcting the power consumption of the heating coil 13, the power consumption is calculated from the input current and input voltage of each heating coil 13 sent by the detection signal 77 from the inverter 72, which will be described later, and the heating power becomes the set value. Thus, an inverter 72 described later is controlled by an inverter control signal 76.

  The inverter 72 is means for supplying electric power to the heating coil 13 and supplies power to the heating coil 13 based on an instruction from the inverter control means 73. Similarly to the inverter control means 73, the inverter 72 is provided for each heating coil 13, and is provided with an inverter right 72a, an inverter left 72b, and an inverter means 72c. Then, the input voltage and the input current of each heating coil 13 are detected and sent to the inverter control means 73 on each detection signal 77. The heater control means 82 controls ON / OFF of the heater 81 while monitoring the temperature in the cooking chamber 26 of the roaster 4 based on the signal from the control means 74. The temperature of the cooking chamber 26 is detected by the temperature detection means 38, input to the heater control means 82 by the detection signal 83, and energization of the upper heating element 27 and the lower heating element 28 is instructed by the control signal 85 from the control means 79. ON / OFF is controlled.

  The heater 81 is a generic name including the upper heating element 27, the lower heating element 28, and the temperature detection means 38 for detecting temperature information in the cooking chamber 26.

  Next, management of power consumption, which is one of the functions of the control means 74, will be described with reference to FIG.

This figure is a schematic flow for the control means 74 to manage so that the total power consumption does not exceed the maximum power consumption of the product. When a thermal power change request is instructed from the operation / display unit 75, the control means 74 confirms whether or not the total power consumption (W _s ) at the time of the change request exceeds the maximum power (W _max ) of the product. However, if the maximum power is not exceeded, the heating / power display of the operation / display unit 75 is changed, the inverter control means 73 or the heater control means 82 is instructed to start cooking and the heating power is changed, and the condition is not satisfied. Indicates that this change setting is not accepted.

Step 91 is a thermal power monitoring that monitors the total power consumption at the present time and the operation of the operation / display unit 75, and monitors the total after changing the power consumption accompanying a new cooking addition request or a current thermal power change request. This is a process, and the total power consumption (W _s ) at the time of the thermal power change request is obtained.

Step 92 is a step of comparing the total power consumption (W _s ) at the time of the thermal power change request obtained in the thermal power monitoring process with the maximum power consumption (W _max ) of the product. If the total power consumption (W _s ) at the time of the thermal power change request is smaller than (W _max ), the process proceeds to a thermal power change process 93 described later, otherwise the process proceeds to an automatic cooking confirmation process 94 described later.

  Step 93 is a thermal power change process for accepting the thermal power change request, and changes the thermal power according to the thermal power change request.

  Step 94 is an automatic cooking confirmation step for confirming whether the setting cooking on the placement unit left 6b is cooking by manual setting or automatic cooking using an automatic menu. The process proceeds to the thermal power changing step 95, and since the thermal power cannot be changed during automatic cooking, the process proceeds to a thermal power change request rejecting process 96 as a final determination.

In step 95, the cooking at the placement unit left 6b is manual cooking, so that the total power consumption (W _s ) at the time of the thermal power change request is automatically placed so as to be within the maximum power consumption (W _max ) of the product. This is an automatic heating power changing step for adjusting the heating power on the left side 6b side. As described above, when the heating power is automatically changed, a notification sound for notifying the cook of the change is sounded or a display is made so that the changed contents can be understood.

  Step 96 is a refusal process in which a request to change the thermal power is not accepted. In this case as well, a warning not to accept is necessary.

  This description is an example in which the priority for maintaining the heating power on the left side 6b is set low. The priority of the thermal power required for each placement unit is automatically changed depending on the combination used. For example, when heating is performed on both the placement unit right 6a and the placement unit left 6b and the roaster 4 or the placement unit center 6c is used for cooking, if the cooking is performed on the placement unit left 6b, The priority on the right side 6a is set low.

  In addition, the priority of the placement center 6c is low regardless of automatic cooking (warming, stew) and manual operation.

  The present embodiment has the above configuration, and the operation thereof will be described next.

  For example, a situation is described in which a user uses a high-fire power at first, and then makes a dish cooked on medium heat. When a pan is placed on the placement unit right 6a and the middle heating power key 49c of the upper surface operation unit right 9a is pressed, the pressed key signal becomes an input signal 80 and is sent to the control means 74. Recognizing that the key 49c has been input, this content is transmitted to the operation display unit 75 as a display signal 79, and the LED lamp 54 of the thermal power key 49c, which is the display unit, is turned on. Then, a number “7” indicating that it is a medium-fired thermal power is lit on the upper surface display portion right 10a, indicating that the backlight color is orange and the medium-fire is set. Next, when the cut / start key 48 on the upper surface operation unit right 9a is pressed, the LED lamp 53 is turned on through the same transmission path (hereinafter, description of the same signal path is omitted), and heating is started.

  When the control means 74 instructs to start cooking, the control signal right 78a transmits that the heating power set to the inverter control means right 73a is "7", and the inverter control means right 73a that has received this is set. Control of the inverter right 72a is performed so as to obtain thermal power, and power control of the heating coil right 13a is performed. The inverter right 72a transmits the detected value of the input voltage and the input current to the detection signal right 77a and transmits it to the inverter control means right 73a. The inverter control means right 73a obtains the power consumption from the detected value. The power of the heating coil right 13a is controlled so as to achieve the power consumption determined in “7” (hereinafter, description of the same signal path is omitted).

  Moreover, the control means 74 will turn ON the ventilation fan 20, if the start of cooking is recognized. When the blower fan 20 is turned on, the blower fan 20 sucks air outside the main body 2 from the intake port 7, and the amount of air blown from the blower fan 20 is distributed to each heat generating component, and from the discharge port 8 while cooling each component. Discharged.

  Air blown from the blower fan 20 is mainly passed through the left and right inverter boards 18, the central inverter board 17, the heating coil unit 25a, the heating coil unit left 25b, and the heating coil unit center 25c in the board case 15. The air that has cooled the left and right inverter boards 18 and the central inverter board 17 is sent to the control board 19, the surface display unit 10, the upper surface operation unit 9, and the heating coil unit 25, and in the heating coil unit 25, direct air from the blower fan 20. And the air that has passed through the substrate are cooled together, and all of the air is discharged from the exhaust port 8. The blower fan 20 may be a sirocco fan or a turbo fan.

  Next, the case where the heating power is changed from medium to high is explained. When the high heat key 49d on the upper surface operation unit right 9a is pressed, the LED lamp 54 of the heat key 49d is turned on, the numeral 10 indicating the high heat power of the upper surface display unit 10a is turned on, and the backlight color is red. become.

  When shifting to stew, if the placement unit right 6a is monopolized by stew cooking for a long time, the efficiency of making other dishes becomes very poor. Therefore, simmering is performed at the placement portion center 6c. Each mounting part is constituted by a plate 3 and is flat, so that the pan can be moved very easily.

  Before moving, set the heating power of the mounting unit right 6a to OFF by pressing the OFF / START key 48 on the upper surface operating unit right 9a, and confirm that the LED lamp 53 is turned off, the heating power value of the upper surface display unit right 10a and the backlight is turned off. To do. When cooking is finished, the blower fan 20 is also stopped (hereinafter, explanation of the blower fan operation is omitted for the same operation).

  After confirming the stop of the thermal power, the pan is moved to the mounting portion center 6c, and this time, the setting power 62 of the upper surface operation portion center 9c is used to set the heating power to “7” of the medium heat while looking at the upper surface display portion center 10c. To do. At that time, the backlight turns orange. Further, the timer key 64 is pressed, the timer time is set with the setting key 62, and the OFF / start key 61 is pressed to check the lighting of the LED lamp 89. After the lighting is confirmed, leave until the timer time reaches zero (the ingredients in the pan are boiled until this time).

  Next, a case where rice is cooked by automatic cooking while cooking at the mounting center 6c will be described. Place a pan (to put the already polished rice in water) on the left side 6b of the mounting part, select rice cooking while watching the display on the upper surface display part left 10b with the menu key 60 on the upper surface operation part left 9b, The amount of rice (number of cups) is set with the setting key 58. When the setting is completed, when the OFF / START key 56 is pressed, the LED lamp 86 is lit and rice cooking is started. When adjusting the cooking level as desired, the UP key 58a or the DOWN key 58b is used while the LED lamp 88 on the setting key 58 is blinking. The display is centered on the upper surface display portion 10c, L is displayed when the setting is weak, and H is displayed when setting is high. In automatic cooking, the food temperature in the pan is detected by the temperature detection element left 21b through the pan and the plate 3, and the detected data passes from the detection signal left 77b to the inverter control means left 73b, and then the control signal left It is transmitted to the control means 74 through 78b. Then, the temperature of the food (pot) is controlled by the control means 74. Moreover, the progress of cooking is confirmed by changes in temperature data.

  When cooking of the cooked rice proceeds and the remaining time is determined, the display on the upper surface display center 10c becomes the remaining time display and decreases in increments of 1 minute.

  Next, the case where it adds and cooks with the vacant mounting part right 6a is demonstrated. The total power consumption is 3.6 kW because rice is already cooked and stewed. The total power consumption is determined when the thermal power is set (when automatic cooking is set). In particular, in automatic cooking, the maximum power consumption determined in advance during cooking is used as a reference. For example, in cooking rice, if the thermal power at the time of cooking is the maximum power consumption used in the process, the high power of 2.5 kW of the thermal power at the time of cooking is the standard. Since the heating power setting is set to “7” in the stew, the power consumption at this time is 1.1 kW. The above is the power consumption at the time of setting, and the total is 3.6 kW. If the maximum power consumption of the main body 2 is 5.8 kW, the remaining 2.2 kW can be used.

  In this state, when the setting is set to “10” (power consumption 2 kW) with high heat on the placement unit right 6a, cooking is started, and then the setting is changed to “11” (power consumption 2.5 kW) with high power. The total power is 6.1 kW, which exceeds the maximum power consumption of 5.8 kW.

  Therefore, the control means 74 automatically changes the setting of the heating power “7” in the mounting portion center 6c to “6” (power consumption 800 W) so that the total power consumption is within the maximum power consumption (when changing). This is notified by a buzzer), and the setting power can be changed to “11”, which is the high power of the heating power on the mounting portion right 6a side.

  At this time, the mounting portion left 6b side was in a state where it was not accepted because it was under automatic cooking, but even in automatic cooking, for example, even if the heating power is slightly reduced such as stew or heat retention, it may not affect the cooking so much Yes, it is possible to change the heating power for each menu.

  Further, when the heating power is changed during the automatic cooking, the heating power may be returned to the original setting when there is a margin in the maximum power consumption.

  In addition, it is possible to provide a thermal power that meets the cook's wishes by finely calculating up to the maximum power consumption, but by determining the combination of the mounting part (roaster part) and the thermal power to be used in advance, It is also possible to inform the cooker of the range of thermal power that can be used in advance by displaying the available thermal power on the display unit and clarifying it.

  Next, the roaster will be described. The user places a cooked product 30 such as fish on the grill 33 of the roaster 4 and operates the fish roast key 66a of the roaster operation unit 12 to select automatic cooking roasting. When the off / start key 67 is pressed, the LED lamp of the off / start key 67 is turned on, and the upper and lower heating elements 27 and 28 and the catalyst heater 37 start energization. At this time, water does not have to be filled in the tray 31 on which the grill 33 is placed.

  Next, the motor 41 is driven, and the coaxial exhaust fan 36 and suction fan 40 rotate. As a result, smoke generated from the cooked food 30 such as fish is deodorized and deodorized while passing through the air purification catalyst 34 from the exhaust outlet 29 provided in the upper rear part of the cooking chamber 26, and passes through the exhaust passage 35 to the upper surface of the main body 2. The air is exhausted to the outside (inside the room) from the exhaust port 8 located on the left side of the frame 14b.

  On the other hand, the suction fan 40 is also rotated by the driving of the motor 41, and the indoor air is sucked into the cooling passage 39 from the air intake 42 at the lower front of the cooking chamber 26, and the saucer is circulated in the cooling passage 39. 31 is cooled and then discharged to the exhaust port 8 through the air discharge port 47.

  At this time, the self-cooling fan 43 provided on the shaft on the other end side of the motor 41 also rotates together with air from the air inlet 45 provided on the bottom surface and the side surface on the main body 2 side in the heat shield chamber 44. After sucking and cooling the motor 41, the motor 41 is discharged from the upper surface discharge hole 46.

  At this time, the air sucked from the air inlet 45 by the self-cooling fan 43 is about 60 to 70 which is the self-heating temperature of the motor 41 by the heat from the cooking chamber 26 being shielded by the heat shielding chamber 44. The temperature can be kept lower than ° C., and overheating of the motor 41 can be suppressed.

  An air purifying catalyst 34 is provided in the vicinity of the exhaust outlet 29 of the exhaust passage 35 connecting the cooking chamber 26 and the exhaust port 8 of the main body 2, and a cooling passage 39 is formed in the lower part of the receiving tray 31. An air intake 42 is provided on the front side of the cooking chamber 26, an air discharge port 47 is connected to the exhaust port 8, and an exhaust fan 36 and a suction fan 40 are disposed in the exhaust passage 35 and the cooling passage 39, respectively. Since the exhaust fan 36 and the suction fan 40 are connected to the coaxial motor 41, the receiving tray 31 is sufficiently cooled by the outside air flowing through the cooling passage 39 at the lower portion thereof, so that the oil does not have to be added to the receiving tray 31. Can prevent smoke and fire, and save time and effort during use.

  Furthermore, the deodorizing effect of the air purification catalyst 34 can be sufficiently exerted and exhausted to the outside of the main body 2. As a result, smoke is emitted from the gap of the cooking chamber 26, particularly from the front roaster door 32 portion to the outside of the main body 2. Prevents leakage and allows the kitchen to be used cleanly.

  When using a roaster, the cooking unit and heat power that can be cooked, for example, when cooking rice is cooked automatically on the left 6b of the mounting unit, the total power consumption is 1.5 kW for roaster and 2.5 kW for cooking, 4 kW in total. Become. Since the heating power cannot be changed in the roaster and the automatic cooking, the remaining 1.8 kW can be used, and the maximum heating power that can be used on the placement unit right 6a is “9” of the high fire.

  Moreover, a total of four places, such as heat retention and a stew, can be used by the mounting part center 6c and the mounting part right 6a. Alternatively, the roaster 4 and the placement portion center 6c can be selected from a maximum of three locations.

  Next, details of the control of the heating coil 13 described above will be described. FIG. 12 is a specific circuit diagram of the heating coil 13, the inverter 72, and the inverter control means 73 shown in FIG. Since the three heating coils 13 are the same, only one will be described.

  The inverter 72 will be described. The AC power source 117 is converted into DC by the rectifying means 102 and connected to a switching unit constituted by a series body of switching elements 103 and 105. Diodes 104 and 106 are connected in antiparallel to switching elements 103 and 105, respectively, and a resonance circuit section formed of heating coil 13 and resonance capacitor 107 is connected between the connection point of switching elements 103 and 105 and the reference point of the DC voltage. Is done. Snubber capacitors 108 and 109 are connected to the switching elements 103 and 105, respectively.

  By switching on and off the switching elements 103 and 105 exclusively at a high frequency, a high-frequency resonance current is supplied to a resonance circuit unit composed of the heating coil 101 and the resonance capacitor 107, and a load disposed in the vicinity of the heating coil 101 is heated.

  The control unit 110 inputs a target power level instruction to be applied to the load from the control unit 74 (FIG. 10), and controls the switching units 103 and 105 so that the output power of the inverter becomes a target value.

  The input current conversion unit 112 converts the output signal of the detection unit 111 that detects the current input from the AC power source 117 to an appropriate level and outputs the converted signal to the control unit 110.

  The input voltage detection means 113 detects the voltage of the AC power supply 117, converts it to an appropriate level, and outputs it to the control means 110.

  The inverter current detection means 115 converts the output signal of the detection means 114 that detects the current flowing through the resonance circuit section into an appropriate level and outputs it to the control section 110.

  The control unit 110 inputs these signals, calculates inverter power that is input to the load, determines the state of the load, suitability for heating, etc., and performs on / off control exclusively for the switching elements 103 and 105. A signal is output and converted to an appropriate drive level for the switching elements 103 and 105 by the level converter 116 to drive the switching elements 103 and 105. Further, the control unit 110 outputs these states to the control means 74.

FIG. 15 is a schematic diagram showing the relationship between the drive frequency of the inverter 72 and the inverter power input to the load, and employs a variable frequency output control system that adjusts the inverter power by varying the frequency. The load of the inverter 72 is a combination of the equivalent inductance and equivalent resistance formed by the heating coil 101 and the pan and the resonance capacitor 107, and the maximum power W _peak can be input when a current flows at the resonance frequency f ₀ . When the switching elements 103 and 105 are driven at a frequency higher than this frequency, the input power decreases. Actually, since the equivalent inductance and equivalent resistance change depending on the material of the load, the frequency f ₁ higher than the resonance frequency f ₀ is set as the limit of the variable frequency, and the rated power W _max is input to the predetermined load at that point. Is set to be able to.

Further, when the drive frequency is set higher, the inverter power decreases. However, since the cut-off current of the switching elements 103 and 105 decreases, the loss of the switching elements 103 and 105 increases. The heat generation of the 103 and 105 and the snubber capacitors 108 and 109 is increased. For this reason, the predetermined frequency (or the frequency at the predetermined minimum power W _min ) is also set as the variable frequency limit f ₂ on the high frequency side. As a result, the actual drive frequency relationship of the inverter 72 is f ₀ <f ₁ <f ₂ (for example, f ₀ = 18 kHz, f ₁ = 20 kHz, f ₂ = 40 kHz).

Note that the inverter power at f ₂ is the lowest power at which the inverter 72 can continuously control the power. However, when power lower than this is applied to the load, a method using ON / OFF control of energization of the inverter 72 is employed. Also, in any stove, the pan to be heated can heat a magnetic pan such as iron or stainless steel, and a magnetic pan such as aluminum or copper cannot be used.

Thus, inverters 72a, 72b are controlling electric power supplied to the heating coil 13a, 13b at the driving frequency range f ₁ ~f ₂ (20kHz~40kHz).

Furthermore, for the reasons described below, the inverter 72c as a driving frequency range f ₁ ~f ₂ (60kHz~90kHz) is selected, and controls the heating coil 13c in this frequency range.

  By the way, the main body 2 is inserted into the inside from the opening provided in the countertop (top plate) of the system kitchen 1. It is installed so that the top plate of the system kitchen 1 and the upper part of the main body 2 are substantially at the same position. Thus, the external dimensions of the main body 2 are regulated by the standard of the system kitchen 1. For this reason, as shown in FIG. 13, the top plate 3 having a heat-resistant glass plate and a metal edge covering the periphery thereof has a horizontally long rectangular glass surface having a width of about 60 cm and a depth of about 40 cm. It has become. The top plate 3 covers the upper surface opening of the main body 2 and is fixed to the main body 2. The top plate 3 has a width dimension of about 75 cm, although the depth dimension does not change in relation to the system kitchen 7.

  If all three openings are induction heating coils within such dimensions, the problem of beat sound (interference sound) occurs. When a pan is heated and cooked by operating a plurality of induction heating coils, when the pan is heated with different heating power, each pan is vibrated by receiving an alternating magnetic field having a different frequency from each induction heating coil. Since the vibration frequency is higher than the audible frequency, there is no problem. However, when the difference between the vibration frequencies of the pans is applied to the audible frequency band, an unpleasant beat sound is generated.

  From the standard of the system kitchen, as shown in FIG. 13, the induction heating coils 13a and 13b (the induction heating coil 13a is arranged under the placement unit right 6a and the induction heating coil 13b is arranged under the placement unit right 6b. The distance between the coil centers is about 30 cm. Further, the distance between the coil centers of the induction heating coil 13c (the induction heating coil 13c is arranged under the placement portion right 6c) and the induction heating coils 13a and 13b is about 20 cm.

  FIG. 14 shows the relationship between the distance between the induction heating coils and the beat sound. The sound pressure level of the beat sound at the distance between the induction heating coils on the left and right of the front part (distance between the centers of the induction heating coil 13a and the induction heating coil 13b), which is about 30 cm in this embodiment, is based on the fan motor sound of the blower fan 20. However, the beat sound is at a level that does not matter to the user. In other words, the distance between the centers of the induction heating coil 13 a and the induction heating coil 13 b is set to a distance at which the sound pressure level of the beat sound is lower than the sound pressure level of the blower fan 20.

  On the other hand, the induction heating coil 13c is the center between the induction heating coil 13a and the induction heating coil 13b, and since it must be disposed in the back of the main body 2, it is between the centers of the induction heating coil 13c and other coils. The distance cannot be reduced. For this reason, beats generated at the distance between the front induction heating coil and the rear induction heating coil (the distance between the induction heating coil 13c and the induction heating coil 13a, the distance between the induction heating coil 13c and the induction heating coil 13b). The sound becomes higher than the sound pressure level generated by the blower fan 20. Incidentally, the sound pressure level of the blower fan 20 is a relatively low value of about 38 dB.

  In order to solve this problem, in this embodiment, the minimum frequency of the power supplied to the induction heating coil 13c is set higher than the maximum frequency of the power supplied to the induction heating coils 13a and 13b.

  Specifically, the induction heating coil 13c is supplied with high frequency power of about 60 kHz to 90 kHz, which is higher than the high frequency power of about 20 kHz to 40 kHz, which is the oscillation frequency supplied to the induction heating coils 13a and 13b. .

  Thus, since the minimum value of the frequency difference is set to 20 kHz which is substantially higher than the audible frequency, the beat sound does not matter to the user. In general, the audible frequency is said to be 20 Hz to 15 kHz. In most cases, 20 kHz or more, which is called ultrasound, cannot be heard. From 15 kHz to 20 kHz, there are individuals who can be heard due to individual differences, and those who cannot. In this embodiment, for the sake of certainty, the minimum value of the frequency difference is set to 20 kHz or more that most people cannot hear.

  In this embodiment, the oscillation frequencies of the induction heating coils 13a and 13b are set from 20 kHz to 40 kHz in substantially the same frequency band. However, even if they are shifted, the beat sound does not cause a problem because of the above-mentioned distance. However, it is necessary to ensure a difference from the lowest frequency of the induction heating coil 13c.

  By the way, in order to prevent the user from being concerned about the beat sound, the object can be achieved even if the frequency of the induction heating coils 13a and 13b is higher than the frequency used for the induction heating coil 13c. However, in this embodiment, the frequency of the induction heating coil 13c is set high. The reason for this will be explained. The induction heating coils 13a and 13b are coils disposed in front of the main body 2, and the induction heating coil 13c is a coil disposed in the back. As described above, the maximum heating power of the coil disposed in front is set high from the viewpoint of usability. In order to increase the frequency, the inductance of the coil must be reduced. In order to reduce the inductance, it is necessary to reduce the number of turns of the coil. Since the output of the coil is proportional to the square of the product of the number of turns and the current, the output cannot be obtained unless the current is increased by the amount corresponding to the reduction in the number of turns. The resistance of the coil is proportional to the frequency, and the loss is expressed as the product of the resistance and the square of the current. From the above, when trying to increase the frequency of a coil with a large output, the loss increases, and it is necessary to reduce the loss in order to keep it within a limited input. By increasing the frequency of the coil whose output is set small and the induction heating coil 13c disposed in the back of the main body 2, measures against beat noise are taken.

  However, we want to further reduce this loss and make effective use of the input as much as possible. The wire diameter φ of the induction heating coils 13a and 13b was set to 0.4 mm, and a coil wire in which 28 wires were twisted was wound to form a substantially disk-shaped coil having a diameter of about 20 cm. On the other hand, the induction heating coil 13c has a wire diameter φ of 0.2 mm, and a coil wire in which 90 wires are twisted is wound to form a substantially disk-shaped coil having a diameter of about 20 cm or smaller.

  Thereby, since the surface area of the coil conducting wire of the induction heating coil 13c can be increased, it is possible to reduce the skin resistance that increases as the frequency increases, and to suppress an increase in the coil temperature that is a loss. Note that the coil conductor may have a strand diameter of φ = 0.2 mm or less and 90 or more strands may be twisted together.

  DESCRIPTION OF SYMBOLS 1 ... System kitchen, 2 ... Main body, 3 ... Plate, 4 ... Roaster, 5 ... Operation panel, 6 ... Mounting part, 9 ... Upper surface operation part, 10 ... Upper surface display part, 12 ... Roaster operation part, 13 ... Heating coil , 17 ... Central inverter board, 18 ... Left and right inverter boards, 20 ... Blower fan, 65 ... Roaster display section, 72 ... Inverter, 73 ... Inverter control means, 74 ... Control means, 75 ... Operation / display section, 81 ... Heater, 82 ... heater control means, 97 ... display, 98 ... line.

Claims (2)

A first induction heating coil; a second induction heating coil; a plate that covers the top surface of these induction heating coils and on which a cooking pan is placed; and an inverter that supplies power to these induction heating coils. In the induction heating cooker that performs by changing the frequency of the current to energize the output control,
The minimum frequency of the frequency band used for the second induction heating coil is set higher by 15 kHz or more than the maximum frequency of the frequency band used for the first induction heating coil,
In the case where electric power lower than the lowest electric power of the first induction heating coil when continuously controlling with the drive frequency of the inverter means as the maximum frequency is applied to the load, the on / off control of energization of the inverter means is used in combination. Induction heating cooker characterized by. A first induction heating coil; a second induction heating coil; a plate that covers the top surface of these induction heating coils and on which a cooking pan is placed; and an inverter that supplies power to these induction heating coils. In the induction heating cooker that performs by changing the frequency of the current to energize the output control,
Each induction heating coil is formed by winding a coil wire in which strands are twisted together,
The minimum frequency of the frequency band used for the second induction heating coil is set higher by 15 kHz or more than the maximum frequency of the frequency band used for the first induction heating coil,
The strand diameter of the second induction heating coil is made smaller than the strand diameter of the first induction heating coil, and the number of strands of the second induction heating coil is reduced to the strand of the first induction heating coil. An induction cooking device characterized by having more than the number of lines.

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